Soil Tillage for Crop Production and Protection of the Environment. Proceedings of the 13th International Conference of the International Soil Tillage Research Organization, held in Aalborg, Denmark, July 24-29, 1994. Vol. 1 and 2.
Jensen, H.E.; Schjonning, P.; (et al.)
The Royal Veterinary and Agricultural University and The Danish Institute of Plant and Soil Science, Denmark.